Let's face it: Playing doctor as kids exposed the most exciting distinctions between boys and girls. But new research has uncovered some less obvious differences between the sexes—specifically, our responses to drugs. Men and women have variations in every organ of the body, says Marianne Legato, M.D., director of Columbia University's Partnership for Gender-Specific Medicine. For starters, our livers produce different versions of enzymes (the chemicals that break down medication), which affects the way we process drugs. We've compiled some crucial drug data to help you avoid getting treated like one of the boys.

Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

What to do about it
If you worry you may be depressed, ask your doctor about Paxil, Prozac, and other selective serotonin reuptake inhibitors (SSRIs). We probably respond better to SSRIs because they extend the time serotonin hangs on to brain cells. Other drugs, such as the monoamine oxidase inhibitors (MAOIs) Marplan and Nardil, and tricyclics like Elavil, don't target serotonin as effectively.

What's the diff?
Women's liver enzymes process this class of tranquilizers more quickly than men's, so the meds don't stay in our systems as long.

What to do about it
If you feel that a prescription sedative, such as Klonopin, Valium, or Xanax, isn't working for you, tell your doctor. You may need a different or more frequent dose. And ask if an antidepressant might work even better.

Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

What's the diff?
High levels of erythromycin, used to treat bacterial infections like bronchitis and strep, can cause irregular heartbeats. Since a woman's heart normally takes a fraction of a second longer to return to rest between beats, further disruption can be life-threatening.

What to do about it
Ask your doctor whether another antibiotic that doesn't affect heart rhythms would be safer.

Prednisolone

What's the diff?
This steroid treatment for asthma is less effective when progesterone levels are high, because the hormone speeds the absorption of the drug. As a result, the meds exit your system faster—and leave you more vulnerable to attacks—during the 2 weeks before your period.

What to do about it
Discuss other meds with your doctor. Sometimes the Pill can regulate progesterone levels; a different steroid may work; or increasing prednisolone when you're premenstrual might be an option.